Liquid-chromatographic study of fluorescent compounds in hemodialysate solutions

We have separated and identified three endogenous, naturally fluorescent substances in uremic hemodialysate by using reversed-phase liquid chromatography with fluorescence detection. Co-chromatography with authentic standards, monitoring peak shifts after enzymic treatment, and spectrofluorescence measurements were used to confirm the identity of indican, tryptophan, and indole-3-acetic acid. Concentrations of indican were about 1.5 those of tryptophan and considerably greater than those of indole-3-acetic acid in hemodialysate samples from 12 renal patients. These three compounds, as well as eight unidentified components, were consistently present in dialysate samples from each of the 12 patients.